1. Field of the Invention
Embodiments described herein relate to apparatus and methods for electrically stimulating cells in the GI system to produce polypeptides for the treatment of various conditions such as diabetes and obesity. More specifically, embodiments of the invention relate to treatment of diabetes by electrically stimulating cells in the gastro-intestinal (GI) system to produce glucose regulating hormones such as incretins.
Due to the increasing consumption of high fat and/or high caloric foods found in the western diet, there has been an epidemic in the United States and other developed countries of diabetes and obesity. Diabetes is a disease in which the body does not produce enough, or properly respond to, insulin, a hormone produced in the pancreas. Insulin is needed to turn sugar and other food into energy. In diabetes, the body either doesn't make enough insulin or can't use its own insulin as well as it should, or both. This causes sugar to accumulate in the blood, often leading to various complications. The American Diabetes Association reported in 2009 that there are 23.6 million children and adults in the United States (equal to about 7.8% of the total population) who have diabetes. While an estimated 17.9 million in the US alone have been diagnosed with diabetes, nearly one in four (5.7 million) diabetics are unaware that they have the disease.
The main types of diabetes include type 1, type 2 and gestational diabetes. Type 1 diabetes results from the body's failure to produce insulin. It is estimated that 5-10% of Americans who are diagnosed with diabetes have type 1 diabetes. Presently almost all persons with type 1 diabetes must take insulin injections.
Type 2 diabetes results from a condition in which the body fails to use insulin properly, combined with a relative insulin deficiency. Most Americans who are diagnosed with diabetes have type 2 diabetes. Many people destined to develop type 2 diabetes spend many years in a state of pre-diabetes: Termed “America's largest healthcare epidemic, a condition that occurs when a person's blood glucose levels are higher than normal but not high enough for a diagnosis of type 2 diabetes. As of 2009 there were 57 million Americans who have pre-diabetes. In the developed world, diabetes is the most significant cause of adult blindness in the non-elderly and the leading cause of non-traumatic amputation in adults. Furthermore, diabetic nephropathy is the main illness requiring renal dialysis in the United States.
Most forms of diabetes have been treatable, in part, since insulin became medically available in the 1920's. Currently, many diabetics monitor their blood glucose using blood glucose meters and give themselves insulin injections one or more times a day. However, this approach has many complications due to the under or over delivery of insulin as well as a long-term inability to regulate blood glucose. Acute complications including hypoglycemia, diabetic ketoacidosis, or non-ketotic hyperosmolar coma may occur if the disease is not adequately controlled. Serious long-term complications include cardiovascular disease, chronic renal failure, retinal damage (which may lead to blindness), nerve damage, and micro-vascular damage (which may cause erectile dysfunction and poor wound healing). Poor healing of wounds, particularly of the feet, can lead to gangrene, and possibly to amputation.
Other forms of drug therapy are also available, such as Metformin (known as GLUCOPHAGE). However, this drug is only indicated for the treatment of type II non-insulin dependent diabetes and has a number of side effects including various gastro-intestinal side effects. Also, it may not be used with patients who have renal disease. Other forms of treatment include implantabable insulin pumps; however, these are costly and ultimately become rejected by the body. Thus there is a need for improved forms of treatment of diabetes and other glucose regulation disorders.
Obesity, defined as a body mass index (BMI) of greater than 30, is a major health concern in the United States and other countries. It has been estimated that one in three Americans and more than 300 million people world-wide are obese. Complications of obesity include many serious and life-threatening diseases including hypertension, diabetes, coronary artery disease, stroke, congestive heart failure, pulmonary insufficiency, multiple orthopedic problems, various cancers and a markedly decreased life expectancy. Many therapies have been attempted for the treatment of obesity including diets, drugs and more invasive treatments such as stomach stapling. However, many fail due to the inability to invoke the satiety signal pathways which indicate to a person when they are full. Research now indicates that many foods being supplied by the foods industry, including those high in salt, sugar and fat, invoke a strong signal response in the brain to keep eating. Thus there is a need for improved forms of obesity treatment including those which can stimulate satiety signals and/or appetite suppression signals to cause the person to stop eating or otherwise suppress their appetite.